The underlying mechanisms: how hypothyroidism affects the formation of common bile duct stones-a review

Prevalence of Thyroid Disorder in Gallstone Disease Patients: A Cross-Sectional Study

Background Gallstone disease (GSD) is one of the most common disorders involving the biliary system. The three types of gallstones include pigment, cholesterol, and mixed stones. Studies have suggested a potential association between thyroid dysfunction and lipid pathogenesis, which influences bile composition. A higher prevalence of thyroid disorders may have an impact on the management of GSD patients. This study aimed to assess the prevalence of thyroid disorders and associated dyslipidemias among individuals diagnosed with GSD. Methodology This cross-sectional, observational study was conducted among 180 eligible patients with a mean age of 47.72 ± 15.29 years. This study included 56 (31%) male and 124 (69%) female patients admitted to the Department of General Surgery, Indira Gandhi Institute of Medical Sciences, in eastern India. A diagnosis of GSD was established based on a radiological investigation (ultrasonography) and was included in the study. A thyroid profile test, a liver function test, and a lipid profile test were done for all patients. Patients with a previous surgical history of thyroid disease and known cases of hypothyroidism taking thyroxin supplements for treatment, as well as uncontrolled diabetes mellitus and hypertension, were excluded from the study. Relevant data were collected and statistically analyzed. Results Among the 180 patients, 122 (67.77%) were euthyroid, 35 (19.44%) had subclinical hypothyroidism, 20 (11.11%) had clinical hypothyroidism, and three (1.66%) had hyperthyroidism. Out of a total of 55 hypothyroidism patients, 37 (67.27%) had dyslipidemias. Conclusions The prevalence of hypothyroidism in GSD was 30%, with a female predominance. Hypothyroidism is a specific risk factor for cholelithiasis, and all patients with GSD who have dyslipidemia should be evaluated for thyroid dysfunction.

Laurence-Moon-Bardet Biedl Syndrome With Cholelithiasis

Laurence-Moon-Bardet Biedl syndrome (LMBBS) is a rare autosomal recessive genetic disorder that is most frequently found in children born from consanguineous marriages. The most prominent clinical characteristics of this syndrome include rod and cone dystrophy, nystagmus, central obesity, polydactyly, hypogonadism in males, renal anomalies, developmental delay, ataxia, speech difficulties, and poor coordination. In this report, we describe the case of a 31-year-old male who had the classical clinical features of LMBBS like developmental delay, retinitis pigmentosa, nystagmus, obesity, hypogonadism, and central obesity, presenting with abdominal pain associated with vomiting and tenderness in the right lower quadrant. The patient was diagnosed with cholelithiasis. This case report emphasizes the atypical complication of cholelithiasis due to the underlying syndrome and the need for further research in this area.

Sex-dependent difference in the relationship between thyroid hormones and gallstone disease in euthyroid subjects

The relationship between thyroid dysfunction and gallstone disease (GSD) has been examined by some observational studies. However, evidence about the relationship between thyroid function and GSD among euthyroid subjects was scarce. The aim of this study was to investigate the association between thyroid function and the presence of GSD in a large-sample euthyroid subjects. A total of 5476 euthyroid subjects who underwent health checkup were included. GSD was diagnosed by hepatic ultrasonography. Conventional risk factors for GSD were assessed as well as serum levels of TSH, TT3, TT4 and Log-transformed TT3/TT4 ratio. A total of 4958 subjects were finally included. Levels of TSH, TT3, TT4, and ln (TT3/TT4) were comparable between GSD and non-GSD group (TSH: 1.73 ± 1.07 vs 1.74 ± 1.07 mIU/L, P = .931; TT3: 1.55 ± 0.40 vs 1.54 ± 0.39 ng/mL, P = .797; TT4: 9.37 ± 2.07 vs 9.49 ± 2.06 ug/dL, P = .245, ln (TT3/TT4): -1.80 ± 0.23 vs -1.83 ± 0.23, P = .130, respectively). Multivariate logistic regression analysis among all subjects revealed that the thyroid function parameters did not reach significant difference. Subgroup analyses showed that the relationship between thyroid function and GSD was different according to gender, with negative association for ln (TT3/TT4) and (odds ratio:0.551, 95% CI: 0.306-0.992, P = .047) and positive association for TT4 (odds ratio:1.077, 1 95% CI: .001-1.158, P = .046) in men. None of the thyroid function parameters was significantly associated with GSD in women. Our findings indicated that low levels of TT3-to-TT4 ratio and high levels of TT4 were significantly and independently associated with GSD among euthyroid male subjects, but not female subjects.

The causal effects of thyroid function and lipids on cholelithiasis: A Mendelian randomization analysis

OBJECTIVE

To investigate the relationship between function of thyroid, lipids, and cholelithiasis and to identify whether lipids mediate the causal relationship between function of thyroid and cholelithiasis.

METHODS

A Mendelian randomization (MR) study of two samples was performed to determine the association of thyroid function with cholelithiasis. A two-step MR was also performed to identify whether lipid metabolism traits mediate the effects of thyroid function on cholelithiasis. A method of inverse variance weighted (IVW), weighted median method, maximum likelihood, MR-Egger, MR-robust adjusted profile score (MR-RAPS) method, and MR pleiotropy residual sum and outlier test (MR-PRESSO) methods were utilized to obtain MR estimates.

RESULTS

The IVW method revealed that FT4 levels were correlated with an elevated risk of cholelithiasis (OR: 1.149, 95% CI: 1.082-1.283, P = 0.014). Apolipoprotein B (OR: 1.255, 95% CI: 1.027-1.535, P = 0.027) and low-density lipoprotein cholesterol (LDL-C) (OR: 1.354, 95% CI: 1.060-1.731, P = 0.016) were also correlated with an elevated risk of cholelithiasis. The IVW method demonstrated that FT4 levels were correlated with the elevated risk of apolipoprotein B (OR: 1.087, 95% CI: 1.019-1.159, P = 0.015) and LDL-C (OR: 1.084, 95% CI: 1.018-1.153, P = 0.012). Thyroid function and the risk of cholelithiasis are mediated by LDL-C and apolipoprotein B. LDL-C and apolipoprotein B had 17.4% and 13.5% of the mediatory effects, respectively.

CONCLUSIONS

We demonstrated that FT4, LDL-C, and apolipoprotein B had significant causal effects on cholelithiasis, with evidence that LDL-C and apolipoprotein B mediated the effects of FT4 on cholelithiasis risk. Patients with high FT4 levels should be given special attention because they may delay or limit the long-term impact on cholelithiasis risk.

Hepatobiliary Thyroid Hormone Deficiency Impacts Bile Acid Hydrophilicity and Aquaporins in Cholestatic C57BL/6J Mice

Women are more prone to develop either hypothyroidism or cholesterol gallstones than men. However, a male predominance in cholesterol gallstones under hypothyroidism was reported. Recently, a novel pathogenic link between thyroid hormone (TH) deficiency and cholesterol gallstones has been described in male mice. Here, we investigate if TH deficiency impacts cholesterol gallstone formation in females by the same mechanism. Three-month-old C57BL/6J mice were randomly divided into a control, a TH deficient, a lithogenic, and a lithogenic + TH deficient group and diet-treated for two, four, and six weeks. Gallstone prevalence, liver function tests, bile composition, hepatic gene expression, and gallbladder aquaporin expression and localization were investigated. Cholesterol gallstones were observed in lithogenic + TH deficient but not lithogenic only female mice. Diminished hydrophilicity of primary bile acids due to decreased gene expression of hepatic detoxification phase II enzymes was observed. A sex-specific expression and localization of hepatobiliary aquaporins involved in transcellular water and glycerol permeability was observed under TH deficient and lithogenic conditions. TH deficiency promotes cholesterol gallstone formation in female C57BL/6J mice by the same mechanism as observed in males. However, cholesterol gallstone prevalence was lower in female than male C57BL/6J mice. Interestingly, the sex-specific expression and localization of hepatobiliary aquaporins could protect female C57BL/6J mice to cholestasis and could reduce biliary water transport in male C57BL/6J mice possibly contributing to the sex-dependent cholesterol gallstone prevalence under TH deficiency.

Hypothyroidism Increases Cholesterol Gallstone Prevalence in Mice by Elevated Hydrophobicity of Primary Bile Acids

Background: Thyroid hormone (TH) deficiency has been associated with increased cholesterol gallstone prevalence. Hypothyroidism impacts hepatic lipid homeostasis, biliary secretion, gallbladder motility, and gallstone (LITH) gene expression, all potential factors contributing to cholesterol gallstone disease (CGD). However, how TH deficiency may lead to gallstone formation is still poorly understood. Therefore, we performed molecular studies in a CGD mouse model under lithogenic conditions and modulation of TH status. Methods: Male, three-month-old C57BL/6 mice were randomly divided into a control (euthyroid) group, a hypothyroid (hypo) group, a gallstone (litho) group, and a gallstone+hypothyroid (litho+hypo) group and were treated for 2, 4, and 6 weeks (n = 8/treatment period). Gallstone prevalence, biliary composition and cholesterol crystals, hepatic expression of genes participating in cholesterol, bile acid (BA), and phosphatidylcholine synthesis (Hmgcr, Cyp7a1, Pcyt1a), and canalicular transport (Abcg5, Bsep, Abcb4) were investigated. Results: Increased cholesterol gallstone prevalence was observed in hypothyroid mice under lithogenic diet after 4 and 6 weeks of treatment (4 weeks: 25% vs. 0%; 6 weeks: 75% vs. 37.5%). Interestingly, neither the composition of the three main biliary components, cholesterol, BAs, and phosphatidylcholine, nor the hepatic expression of genes involved in synthesis and transport could explain the differences in cholesterol gallstone formation in the mice. However, TH deficiency resulted in significantly increased hydrophobicity of primary BAs in bile. Furthermore, downregulation of hepatic sulfonation enzymes Papss2 and Sult2a8 as well as diminished biliary BA sulfate concentrations in mice were observed under hypothyroid conditions all contributing to a lithogenic biliary milieu as evidenced by microscopic cholesterol crystals and macroscopic gallstone formation. Conclusions: We describe a novel pathogenic link between TH deficiency and CGD and suggest that the increased hydrophobic character of biliary BAs due to the diminished expression of hepatic detoxification enzymes promotes cholesterol crystal precipitation and enhances cholesterol gallstone formation in the bile of hypothyroid mice.

Thyroid Dysfunction and Cholesterol Gallstone Disease

Cholesterol gallstone disease (CGD) affects 10-15% of the adult population worldwide and the prevalence increases as a result of longer life expectancy as well as rising obesity in the general population. Beside well established CGD risk factors including environmental and genetic determinants (LITH genes), a correlation between thyroid dysfunction and CGD has been suggested in several human and murine studies. Although the precise underlying mechanisms are poorly understood, thyroid hormones may impact bile flow, bile composition and the maintenance of the enterohepatic circulation. Further there is evidence that thyroid hormones possibly impact LITH genes which are regulated by nuclear receptors (NRs). A better understanding of the CGD pathomechanisms might contribute to personalized prevention and therapy of highly prevalent and economically significant digestive disease. This review presents the current knowledge about the association between CGD and thyroid hormone dysfunction.

Sex-Dependent Claudin-1 Expression in the Liver of Euthyroid and Hypothyroid Mice

BACKGROUND

In the liver the tight junction protein claudin-1 plays an important role in bile secretion by maintaining the paracellular barrier of bile canaliculi and the bile duct. A diminished bile excretion has been found in hypothyroid patients, and the prevalence of gallstones is increased in hypothyroidism. This association, however, only applies for men and is in contrast to the well-established female preponderance of biliary disease in the general population.

OBJECTIVES

We hypothesized that hypothyroidism could lead to altered claudin-1 expression in the liver, and that this effect may be sex specific.

METHODS

We characterized claudin-1 expression and localization in livers of euthyroid and hypothyroid male and female C57BL/6NTac mice by real-time PCR, Western blot and immunofluorescence.

RESULTS

Claudin-1 is expressed in canalicular regions and the bile ducts of the murine liver. Livers of female mice showed lower claudin-1 expression than male livers. In hypothyroid livers, female animals showed an elevated claudin-1 expression, whereas reduced claudin-1 expression was found in male animals compared to the euthyroid controls.

CONCLUSION

We demonstrate a correlation between claudin-1 expression and hypothyroidism in the murine liver. Furthermore, a sex-dependent alteration of claudin-1 expression was found.